Engine



H. JUNKERS Feb. 18, 1936.

`-ENGINE Filed Nov. 9, 1929 Patented feb. 18,

. ENGINE cHugo Junkers, Dessau, Germany, assigner toI My inventionrefersztoiengines and more especially to the kind of engines in whichtwo pistons are arranged in'each cylinder for reciprocation in oppositedirections, these pistons acting ontwo separate crank shafts, one ateach endof the plston,fwhich are positively coupled with each other bymeans of suitable. gearing, such as toothed wheels, chains, crank gear,orthe like.

If the power generated by th engine is transmitted only by one Aof theseshafts or by a part of the intermediate gearing adjoining one of theshafts, these gears are called-.up on to transferV that half of theoutput, which is transmitted by the second shaft, towards the first`crank shaft, `and. are therefore required to be comparatively heavy andlarge, so that considerable losses of power are incurred.

The present invention contemplates a considerable reduction of thepercentage of power tobe transmitted from the intermediate gearingltothe place ofconsumption, in order to effect a saving of space,weight, cost, and power4 losses.

To this end I employ means well known per seY for making the percentageof work to be transmitted by each of the two crank shafts unequal and Icause the major portion of the engine output to be taken oif the moreheavily loaded shaft, or if the intermediate gearing has the form of" atoothed wheel gearing with a plurality Vof intermediate wheels arranged'in series, from the axle of the toothed wheel directly adjoiningthisshaft. I thereby obtain that the power to be transmitted by theintermediate gearing is less firm: Junkers-Motorenbau Germany G. m. b.H., Dessau,V

Application November 9, 1929", serial No. 406,090

Germany November 20, 1928 than one half of the total power.

Inbrder to obtain'an unequal .distribution of work onto the two crankshafts, I may for instance use the following means: l

(a) In internal combustion engines, the cranks of .those pistons, whichtransmit the major amount of power, are made to lead the cranks of thepistons transmitting the minor amount of power.

(b) Pistons ployed;

In the drawing amxed to' forming .part thereof. twol modications of anengine embodying my invention are illustrated diagrammauesuy by way' In.the drawing of example.

different strokesare ema.

(c) That crank shaft receiving thel minor amount of power is ,utilizedlfor operating the auxiliary, devices to be-driven by the engine, such asfor instance the pumps for cooling water, combustion air, f fuel,`lubricant, etc., the electrical this speci-ca'tion and Fig. 1 is adiagram which illustrates the unequal distribution of the output, which.results in an internal combustion engine with double pistons from theleading of the crank for the exhaust piston.

Figs. 2 and 3 are an axial longitudinal section `and an axial crosssection, respectively, of the first,i and v Figs. 4 and 5 are similarviews of the second modification.

Fig. l illustrates thev pressure-volume-diagrams corresponding to the`thrust of an internal combustion engine having two pistons operating inopposite directions, the cranks of these pistons u relative to theirextreme positions. The dla.-

' gram surface bordered by the curved line I corresponds to thepercentage of. power which is transmitted to the piston controlling theexhaust ports, which is connected with the leading crank. 20

The surface bordered by the curved line 2 corresponds to thg percentageof power transmitted by the piston controlling the scavenging ports,this latter percentage being considerably lower than the one transmittedby the iirst mentioned 25 piston. The relation between the twocharacteristics and the angle of lead d can easily be guessed from thediagram. i n

Referring now to Figs. 2 and 3, I0 area plurality of juxtaposedcylinders, and II, I2` are two` 30 pistons arranged in each cylinder forreciproca.- tion in opposite directions. I3 are the intake ports for thescavenging air or mixture arranged f-at one end of the working chamberof each cylinder. opposite end. of the working chamber. The pistons vI Icontrolling the scavenging ports I3 transmit power yto the crank shaftl5, the pistons I2 controlling the exhaust ports operate the crank shaftI6. The two shafts are positively con- 40 nected with each other bybevel gearlngs I'I,y I8, and I9, 20, respectively, and an intermediateshaft 2l in such manner that each crank of shaft IB leads with regard tothe crank, belongingi'to the same cylinder, of lshaft I5 by a predeter-45 mined angle a (Fig. 3). 'Ihe power generatedV by the engine istransmitted for instance to a water or air propeller 23 driven by theengine by means of an extension 22 of the crank shaft I6 arranged on theexhaust side. In consequence of `this ar- 50 rangement shaft I6 is actedupon with more than one half of the engine output, and in consequencethereofl the intermediate gearing I1 to 2| is not called upon totransmit one half, but less thanv onehalfofthetotaloutrmt;Inordertofun-gg being staggered through alpredeterminedangle 15 I4 arethe exhaust ports arranged at the 35 ther reduce the power to betransmitted by this gearing, the auxiliary devices 30, 3|, to beopercrankshaft I5'. 'I'he two crank shafts are positively coupled bytoothed wheels I1', I8', I9', 20', arranged in series, in such mannerthat the crank l shaft rI6' leads with respect to the shaft ISby anangle a, whereby also an increased transmission of power to shaft I6' isobtained. In order to further increase the percentage of powertransmitted to shaft I6', the radius of the cranks oi shaft I6 is madelonger than theI radius of the cranks of shaft I5. Here power istransmitted by means of the extension 25 of the axle of the intermediatewheel 20' directly adjoining crank shaft I 6', so that only thisintermediate wheel is more heavily strained, while the otherintermediate wheels Il' to I 9' are much less loaded. According to thediameter of the toothed wheels 2i'- and 22' mounted on the crank shaftsand of the intermediate wheel 20 transmitting power, an increase orreduction of the number of revolutions can be obtained for the powertransmitting axle 25 with iespect to the crank shafts. Auxiliary devices38', which are to be operated by the engine, are here again connected tothe crank shaft I5'. Y

The most advantageous embodiment of my invention, comprises atwin-shaft, two-cycle internal combustion 'aeroplane engine, a pluralityof juxtaposed cylinders having intake and exhaust ports, a pair ofcrank-shafts one mounted at each end of-said cylinders rotating at thesame speed, a pair of pistons mounted to reciprocate in each of saidcylinders in opposite directions and operatively connected by means ofcrank arms to transmit power to said crank-shafts, one of said pistonsbeing adapted to control said intake ports and the other being adaptedto control said exhaust ports, means including crank arms of unequalcrank throw producing an unequal distribution of power to saidcrank-shafts; the crank arms having the greater crank throw transmittingthe major amount of power; a driven part `coupled to both crank-shafts,and means for synchronizing the operation of said crank-shafts and fortransmitting power from the crank-shaft receiving the minor amount ofpower to said driven part, said synchronizing means being of such weightand strength as to be adapted to transmit less thanvhalf of the totalpower delivered' to said driven part, the crank-shaft receivingthe majoramount of power being more closely coupled to said driven part than saidshaft receivingof power, I mean that the former shaft is 'closer to thedriven part or is coupled therewith more directly or through fewermoving' parts or through ore sturdy mechanism.

I wish it to be understood that I do not desire to be limited to theexact details of construction shown and described for obviousmodifications will occur to a person skilled in theart.

1. In a twin-shaft', two-cycle, internal combustion engine, a pluralityof juxtaposed cylinders having intake and exhaust ports, a pair ofcrankshafts one mounted at each end of said cylinders rotating at thesame speed, a pair of pistons mounted to reciprocate in each of saidcylinders in opposite directions and operatively connected by means ofcranks and crank arms to transmit power to said crank-shafts. one ofsaid pistons being adapted to controlA said intake ports and the `otherbeing adapted to control said exhaust ports, means 'including leadingand lagging cranks producing an unequal distribution of power to saidcrank-shafts, said leading cranks, beingconnected to the crank-shaftreceiving the major amount of power. a driven part coupled to bothcrank-shafts, and means for synchronizing the operation of saidcrank-shafts and for transmitting power from the crank-shaft receivingthe minor amount of power 'to said driven part, said synchronizingmeans' being of such weight and strength as to be adapted to transmitless than half of the total power delivered to said driven part, thecrank-shaft receiving the major amount of power -being more closelycoupled to said driven part than said shaft receiving the minor amountof power.

2. 'I'he engine of claim 1 wherein the driven part is mounted on thecrank-shaft receiving the major amount of power.

3'. The engine of claim 1 wherein said crankshaft receiving the minoramount of power is coupled to more auxiliary machinery than saidcrank-shaft receiving the maior amount o power. r

4. 'I-'he engine of claim 1 wherein said vsynchronizing means comprisesa train of gears, the driven member being mounted on one of the shaftsof said gears.

' HUGO JUNKERS.

